Auto merge of #3791 - sunng87:port-handlebars-to-serde, r=alexcrichton

Use serde type system for handlebars

This will help cargo to drop rustc_serialize as dependency (#3682). Handlebars actually supports using serde_json as its type system instead of rustc_serialize. And I'm planning to drop rustc_serialize in future releases.

Cargo.toml

@@ -28,7 +28,7 @@ fs2 = "0.4"
 git2 = "0.6"
 git2-curl = "0.7"
 glob = "0.2"
-handlebars = "0.25"
+handlebars = { version = "0.25", features = ["serde_type", "partial4"], default-features = false }
 libc = "0.2"
 libgit2-sys = "0.6"
 log = "0.3"

src/cargo/util/template.rs

@@ -18,7 +18,7 @@ pub fn toml_escape_helper(h: &Helper,
                           _: &Handlebars,
                           rc: &mut RenderContext) -> Result<(), RenderError> {
     if let Some(param) = h.param(0) {
-        let txt = param.value().as_string().unwrap_or("").to_owned();
+        let txt = param.value().as_str().unwrap_or("").to_owned();
         let rendered = format!("{}", toml::Value::String(txt));
         try!(rc.writer.write_all(rendered.into_bytes().as_ref()));
     }
@@ -30,7 +30,7 @@ pub fn html_escape_helper(h: &Helper,
                           _: &Handlebars,
                           rc: &mut RenderContext) -> Result<(), RenderError> {
     if let Some(param) = h.param(0) {
-        let rendered = html_escape(param.value().as_string().unwrap_or(""));
+        let rendered = html_escape(param.value().as_str().unwrap_or(""));
         try!(rc.writer.write_all(rendered.into_bytes().as_ref()));
     }
     Ok(())